How are solar panels installed? We reveal all and bust the myths

One of the main elements to consider before installation is the orientation of your roof as this plays a part in how much sun it’s exposed to A south-facing roof will produce the largest amount of energy, and while an east or west-facing roof will also work, a north-facing roof will receive a much smaller amount of direct sunlight.  

Sustainable energy and heating expert David Hilton from Heat and Energy Ltd , guides us through the process of what’s involved when installing solar PV panels and tells us: “it’s actually a fairly simple process, but it can have some disruptive pitfalls along the way.” 

Once you’ve selected about three installers, you can ask them for a quote. A quote is usually created by first doing a desktop survey using software that can map your rooftop and give you a fairly accurate idea of the installation size, cost and annual generation yield.

Once you accept the quote from the installer you’re happy with, a home survey visit is planned to confirm the details. This involves checking there are no additional obstacles, the position of the equipment and cabling is confirmed, and the condition of the roof structure and cladding (tiles) is sound. Any amendments are then added to the quote. If you choose to go ahead, an installation date can be scheduled.

When the installation has a generation capacity of 16 amps or less (this is a maximum generation output of around 3.72kW – or 9-to-10 panels), the installation does not need any permission from the distribution network operator (DNO), which controls the electric grid.

If you have three-phase electricity (which, in simple terms, consists of three electricity ‘phases’ or supplies, which help balance appliances out so they don’t all run off the same phase), you can install 16 amps per phase, so three times more than the normal single phase (230V) supply.

As soon as the installation begins, scaffolding will be erected to give access to the roof.  Sometimes a scaffold deck system is also used, providing a safe platform for the installers. 

Tiles removed – the installers will then lift some of the tiles to screw robust hooks to the roof trusses (or structural elements of the roof).

There are different hooks for different roof types, and the tiles are often trimmed or notched to fit snuggly back around the roof hooks.

The rails are then fitted to the roof hooks so that they are mounted horizontally across the roof.

The panels are then mounted onto the aluminium rails and wired together with the service cables, which are then fed to the loft area. 

Any pigeon proofing or other protection such as netting is fitted around the panels to stop birds nesting underneath. 

Back inside the house, the electrician will mount the inverter – this is the device that converts direct current (DC) that the panels generate into the alternating current (AC) that can be used in the home.The solar inverter allows the panels to convert sun into energy. 

Once mounted, the inverter is then connected to the main consumer board in the home, allowing the energy generated to be used on site.

A route needs to be planned for the wiring from the loft to get to the inverter (the inverter can be installed in the loft, garage or anywhere convenient in the home). The cables from the inverter then need to be run to the consumer board.  

While the above process is standard for typical solar panels, there are exceptions.

When fixing solar panels in an ‘above the roof’ system, the tiles or slates are removed and a roof hook is fixed to the wooden rafters. Although extra time and cost needs to be allocated when working with slate tiles, as Robinson explains, “there’s lots more work with slate roofs,” he adds, “because you need to add a flashing unit, whereas with tiled roofs, you don’t.”   

The flashing acts as a waterproof solution that sits around the roof bracket, and the slate will then need to be trimmed to fit around the flashing.  

An integrated system gives a sleeker finish as the solar panels are installed in line with the roof tiles. Robinson explains: “The roof is stripped, and batons are put in place to fix a tray, which the panels sit within.” 

When installing solar panels, there are two elements that can increase the cost – inadequate electrics and issues with the roof.

The electrical system needs to be robust enough to connect the solar panel inverter, which converts the direct current (DC) produced by your solar panels into an alternating current (AC) to power your home. “Having a spare fuse on a distribution board won’t be sufficient in many instances,” says Robinson. “The internal wiring and consumer unit/fuse board may be too old and the test certificate out of date with newer, superseded regulations now in place”.

The structural strength of the roof and how old it is can also cause an issue. “Tiles and slates that have been in situ for a long time can be very fragile,” says Robinson. “All of this needs to be considered.”

​​“The fitting time depends on how much work needs to be done to get the roof and electrics in good shape,” says Robinson, “And it’s difficult to know the condition of the roof until you’re physically on it.” ​​​ 

However, as a general guide, Neil Woolley, customer acquisition director at the Octopus Energy Group says: “Standard installs can be completed within two-three days, and bigger installs can take between three-four days.”  

Time will also need to be scheduled for putting up and taking down scaffolding, unless you have a single-storey property, where it might not be required. However, some installers will still recommend using scaffolding when fitting solar panels to single-storey properties.  

Robinson says that setting up your solar system to export electricity doesn’t take any extra time but warns: “Make sure your installer has an MSC certificate to enable you to export to the grid.” 

Using an MSC-certified installer is also a requirement to qualify for the Smart Export Guarantee, allowing you to receive payment for the electricity you feed back to the grid.  

“When your installation is complete, you’ll start generating electricity straight away,” says Woolley, “but it will take a couple of weeks before your export MPAN (Meter Point Administration Number) is ready and you can start getting paid for the energy you export.” 

It’s easy to monitor your energy production and output as Woolley explains: “Most hardware comes with mobile and web apps that allow you to see your usage both in real-time and cumulative over time.”  

 If you have a south-facing roof that’s not shaded, you’ll naturally gain the maximum benefit from the solar panels. However, if your roof faces east or west, you can still benefit, although the ​​Energy Saving Trust estimates your yield will be around 15-20% less.  

 Unfortunately, if you’ve got a north-facing roof, solar panels aren’t for you. “It wouldn’t be suitable,” says Woolley, “as the part of your roof with the panels on would need to see the sun throughout the day.”  

Solar Energy UK, in its Value of Solar Heat Report 2022 states that a typical 3kW to 4kW system will include 10-14 panels. Although other organisations estimate differently, there are many variables involved. These include how much time you spend at home and whether you charge an electric car.

Reviewing your energy needs will help determine the number of panels you require, so that you don’t pay for more than you need or find yourself still relying on the grid as you haven’t installed the correct number of panels.

The Energy Saving Trust’s solar energy calculator will help you determine how many solar panels you’ll need.

“Customers will need a clear space on a pitched roof that can accommodate at least six solar panels,” says Woolley.

However, the number you choose will depend on your energy requirements, whether you want to supply energy to the grid and how much space you have.

As an indication of the size of each panel, Octopus Energy’s panels measure 1.7m (5.5ft) x 1.1m (3.6ft) and require a 40cm (16in) gap between the edge of the roof and the solar system.

The Energy Saving Trust says you can expect the average domestic system, based on 3.5kWp, to take up a roof area of approximately 20 sq m.

Saga Exceptional recommends that you check with your local planning office for guidance before making a financial commitment. Solar panels are usually designated under the permitted development rule, although a few exceptions exist.   

Solar panels are also subject to building regulations, so use a certified installer.

“One option is to go directly to an installer,” says Gareth Simkins, senior communications adviser at Solar Energy UK. ‘We’d also advise using a member of Solar Energy UK.”

Being a member of Solar Energy UK means that all domestic installers are Microgeneration Certification registered. Member businesses also need to achieve a minimum turnover. Simkins adds: “They tend to be larger and more established, so are more likely to have stable finances.”

It’s also worth checking that your installer is assigned to the Renewable Energy Customer Code (RECC) and the Microgeneration Certification Scheme (MCS), as this will give you extra protection should anything go wrong. 

“Another option is to go through a company such as Otovo, which does the hard work of finding an installer for you,” says Simkins. “Although new to the UK, it’s a trustworthy and established operation in the rest of Europe.”

What can you expect once you’ve found an installer? Simkins explains: “They’ll visit your home, assess what is physically viable and appropriate, then provide a quote.” But, be warned, “waiting times for installation can be long,” he says, “largely due to rising demand.”